Simulative keystone

ABSTRACT

A composition and process for producing objects of simulative keystone, a naturally occurring fossiliforous coral formation which is indigenous to the Florida Keys. A water-extended polyester resin is mixed with a cobalt salt and a tertiary aromatic amine, followed by the addition of a ketone peroxide, and cast into a keystone mold. Curing takes place rapidly at room temperatures, yeilding a molded object closely resembling natural keystone in color, texture, appearance, and other superficial characteristics.

United States Patent 1 Killmer SIMULATIVE KEYSTONE [75] Inventor:Roberta Killmer, Cocoa Beach, Fla.

[7 3] Assignee: Meridian Decorator Accessories and Imports, Inc.,Merritt Island, Fla.

[22] Filed: Feb. 8, 1971 [21] App]. No.: 113,734

[52] US. Cl. 161/19, 161/231, 161/233, 264/219, 264/220, 264/225,160/292 E [51] Int. Cl B321) 27/36, B44f 7/00 [58] Field of Search161/19, 231, 233; 264/219, 220, 225; 260/292 E [56] References CitedUNITED STATES PATENTS 3,546,052 12/1970 McNamara 161/19 3,312,761 4/1967Vida 264/77 OTHER PUBLICATIONS Leitheiser, Polyesters, Modern PlasticsEncyclope- Nov. 20, 1973 dia (1969-1970), Vol. 46: No. 10A (October,1969). pp. 172, 176.

Primary Examiner-Alfred L. Leavitt Assistant Examiner--Robert A. DawsonAttorney-Oblon, Fisher & Spivak [5 7] ABSTRACT A composition and processfor producing objects of simulative keystone, a naturally occurringfossiliforous coral formation which is indigenous to the Florida Keys. Awater-extended polyester resin is mixed with a cobalt salt and atertiary aromatic amine, followed by the addition of a ketone peroxide,and cast into a keystone mold. Curing takes place rapidly at roomtemperatures, yeilding a molded object closely resembling naturalkeystone in color, texture, appearance, and other superficialcharacteristics.

1 Claim, N0 Drawings SIMULATIVE KEYSTONE BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to a composition andprocess for producing molded objects of simulative keystone. Moreparticularly, this invention relates to a composition and process forproducing molded objects of simulative keystone by casting awater-extended polyester resin mixture in keystone molds to produceobjects having the appearance of natural keystone.

2. Description of the Prior Art Keystone is a naturally occurringfossiliforous material found primarily in the Florida Keys, and is muchlike a coral formation in appearance. It usually has an off-white colorand a fine surface texture resembling that of an egg shell. Because ofits pleasing appearance, shapes, texture, and color, keystone has founda wide variety of uses for decorative objects such as lamp bases,figurines, urns, fireplace fronts, and stepping stones. In the area ofthe Florida Keys, keystone is also often used in structural applicationssuch as columns and building sidings.

While the demand for keystone has been great and continues to increase,both in the area of its chief natural location near the Florida Keys andincreasingly elsewhere, keystone has heretofore been available only inthe natural state. Not only has the large demand for keystone beendifficult to meet due to specimen collection and shipment difficulties,but equally important is the fact that these growth forms containfossils and accordingly are reformed naturally only over long periods oftime. The commercial demand for keystone depletes existing naturalformations in readily accessible areas which will not reform for manyyears. Since the most highly prized features of keystone are found inits shape, texture, color, and other superficial characteristics, itwould be highly desirble to be able to synthetically produce objectswhich simulate these features, thereby greatly decreasing the harvestingof natural keystone formations in the limited geographical areas inwhich they occur. Furthermore, such a process could enable wider use ofsuch objects, since naturally occurring keystone has somedisadvantageous properties such as being subject to breakage inhandling. Additionally, a process for producing such objects without thenecessity of large capital investments in molding equipment wouldfurther extend the availability thereof. The present invention fillssuch needs.

Many naturally occurring minerals and stones of various typeshave beenmade synthetically, and many materials approximating the characteristicsof a corresponding naturally occurring material, such as syntheticmarble, have been produced from specialized compositions. The presentinventor is unaware of any methods in the prior art for producingsimulative keystone.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of thepresent invention to provide a molded material having the superficialcharacteristics of naturally occurring keystone.

A principal object of the present invention is to provide a compositionand process for producing molded objects of simulative keystone.

Another object of the present invention is to provide a composition andprocess for producing molded objects of simulative keystone usingreadily available materials and techniques.

A further object of the present invention is to provide a means forincreasing the availability of decorative objects closely resemblingnatural keystone while reducing the need to harvest naturally occurringkeystone formations from the sea floor.

Briefly, these and other objects are attained in one aspect of thepresent inventon which provides a composition and process for producingobjects of simulative keystone by molding a water-extended polyesterresin mixed with a cobalt salt, a tertiary aromatic amine, and a ketoneperoxide, in a mold which is taken from natural keystone. Curing takesplace rapidly at room temperatures, yielding a molded object closelyresembling natural keystone in color, texture, appearance, and othersuperficial characteristics.

The above and other objects, features, and advantages of the inventionwill become more fully apparent to those skiled in the art from thefollowing description of illustrative embodiments of the invention,which are presented by way of example and not by way of limitation.

DESCRIPTION OF PREFERRED EMBODIMENTS Water-extendable polyester resinsmay be any of the known linear unsaturated polyester resins known in theart to which additives such as those taught, inter alia, by Will in US.Pat. No. 3,256,219, incorporated herein by reference, have been added toprevent pimpling on water extension. In general, such resins havemolecular weights of 1,000 3,000, preferably from 1,500 2,000, and areobtained in a syrup-like solution of the linear unsaturated polyesterand a normally liquid vinyl monomer such as styrene, a-methyl styrene,vinyltoluene, or the like. A inhibitor may also be included in thesolution to prevent premature polymerization. Addition of an activecatalyst overcomes the inhibitor, resulting in a three-dimensionalcross-linked polymer as the vinyl monomer reacts with the unsaturationin the linear polyester chain.

While suitable water-extendable polyester resins include polyestersprepared from phthalic anhydride, maleic anhydride, and propylene glycolto which the aforementioned additives have been added to make themwater-extendable, particularly preferred resins are those mixtures ofabout 40 percent polyesters prepared from isophthalic acid, maleicanhydride, diethylene-glycol and propylene glycol, and correspondinglyabout 60 percent styrene. The amount of styrene used for cross-linkingis not critical within a wide range, and thus will normally bedetermined by the viscosity requirements for a given application. Theaforementioned preferred water-extendable polyester resins have anemulsion viscosity at 77 F. (Brookfield LTV using a No. 3 spindle at 30RPM) of 800 cps. when extended with 50 percent water and 1,800 cps. whenextended with 60 percent water.

While a wide variety of water-extended polyester resins, monomers, andcatalyst systems are suitable for the purposes of the present invention,preferred materials such as Ashland AIRPOL WEP 660 (Trademark) when usedin combination with a ketone peroxide such as methyl ethyl ketoneperoxide and a synergistic proof the polyester resin at roomtemperature, thereby greatly simplifying the choice of mold materialsand eliminating requirements for any expensive apparatus. Furthermore,use of the above combination of ingredients as described herein resultsin a final product virtually indistinguishable from natural keystone insuperficial properties. While cobalt salts alone promote the breakdownof ketone peroxides at room temperature, the tertiary aromatic aminesare ineffective when used alone for this purpose. Tertiary aromaticamines such as dialkyl anilines, particularly dimethylaniline,diethylaniline, and the like, do, however, promote the breakdown ofdiacyl peroxides such as benzoyl peroxide at room temperature, while thecobalt salts are ineffective for this purpose. As is known in the art,dimethylaniline is synergistic when used with cobalt salts for promotingresins catalyzed with methyl ethyl ketone peroxide, and this combinatonis greatly preferred because of the rapid room temperature gellingcharacteristics of polyester resins cured with this combination. Otherdialkyl anilines, such as diethylaniline, may also be used withcomparable results. Since the methyl ethyl ketone peroxide initiatescuring rather rapidly in such a system, it is preferably the lastingredient to be added to the composition.

If desired, dry earth powders may be added to obtain various colorationsin the final product. While other types of dyes may also be used, thedry earth powders are preferred because they yield a final product whichretains the dry look characteristic of natural keystone. The preferreddry earth powders are yellow ochre, yellow oxide, raw umber, raw sienna,brick red, green oxide, red oxide, Venetian red, blue cobalt, burntumber, lampblack, or black oxide.

Particularly suitable water-extendable polyester resins include the WEP(Trademark) resins produced by Ashland Chemical Company, the POLYLITE(Trademark) water-extendable polyester resins produced by ReichholdChemical Company, and other similar materials. It is important to dilutethe water-extendable polyester syrup with water in a ratio of at leastabout 1 part polyester syrup to 2 parts of water, and it has been foundthat the syrup may be diluted with 4 parts of water per part of syrup toyield a molded product which superficially resembles naturally occurringkeystone. This is surprising in view of the fact that waterextendablepolyester resins are seldom suitable for use in dilutions aboveapproximately 60 percent water to 40 percent resin syrup. Waterextension is important not only in obtaining the right consistency inthe final molded product, but also in achieving an accurate reproductionfrom the mold by reducing the viscosity of the composition.

While the proportions of the other added materials are not critical withany wide range, satisfactory results have been attained by the use of to30 milliliters per gallon of a 12 percent cobalt solution, 15 to 45milliliters per gallon of methyl ethyl ketone peroxide as a 60 percentsolution in dimethyl phthalate, and to 30 milliliters per gallon ofdimethylaniline.

The following Examples are presented to illustrate preferred embodimentsof the present invention, For each Example, a rubber mold was made of anaturally occurring keystone sample. As previously mentioned, the orderof addition of the various components may be varied, except that due tothe high reactivity of methyl ethyl ketone peroxide, it is generallyadvantageous to add it as the last ingredient. All percentages are byvolume, unless otherwise indicated. The water-extended polyester resinused in the following examples was AIR- POL (Trademark) WEP (Trademark)660, obtained from Ashland Chemical Company. The cobalt was added as a12 percent solution, available from Resin Coatings Company, Miami,Florida, as Cobalt 12%. Methyl ethyl ketone peroxide was added as a 60percent ethyl ketone peroxide in dimethyl phthalate solution, availablefrom Reichhold Chemicals, Inc. as Methyl Ethyl Ketone Peroxide 60. Thedimethylaniline was added in undiluted form.

EXAMPLE 1 To 4 gallons of water-extended polyester resin was added 16gallons of water, 300 cc. of cobalt solution, cc. of dimethylaniline,and 300 cc. of methyl ethyl ketone peroxide solution. The methyl ethylketone peroxide was added just prior to pouring the material into themolds. The entire mixture was then cast into molds taken from naturalkeystone, and allowed to remain at ambient room temperature for 15 to 60minutes. The curing reaction is exothermic, and upon removing the curedproduct from the molds, a product was obtained which closely resemblednatural keystone in superficial appearances.

EXAMPLE 2 To 2 gallons of water-extended polyester resin was added 8gallons of water, 45 cc. of dimethylaniline, and cc. of cobalt solution.Just prior to pouring into the molds, 150 cc. of methyl ethyl ketoneperoxide was added and mixed thoroughly with the other ingredients. Thematerial was allowed to remain at ambient temperature for approximately15 minutes until the cured product was too hard to take a fingernailimprint. The only critical feature with respect to curing time is thatthe material must be left in the mold until it becomes sufficiently hardso that there will not be any breakage when it is removed. Upon removalof the cured product from the molds, a molded object was obtained whichclosely resembled naturally occurring keystone.

EXAMPLE 3 80 gallons of water was added to 20 gallons of waterextendedpolyester syrup. 1,500 cc. of cobalt solution and 750 cc.dimethylaniline were then added, followed by 1,500 cc. of methyl ethylketone peroxide solution. The entire mixture was poured into rubbermolds taken from natural keystone and allowed to cure at ambienttemperature for 15 to 60 minutes. Upon removal from the mold, a moldedobject was obtained closely resembling natural keystone in superficialproperties.

It will be appreciated that while the foregoing disclosure relates onlyto a preferred embodiment of the invention for preparing objects ofsimulative keystone, it is capable of numerous modifications oralterations which may be made by those skilled in the art withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed as new and intended to be secured by Letters Patent ofthe United States is:

1. A molded object closely resembling natural keystone in color,texture, appearance and consistency which comprises a cured waterextendable polyester resin prepared by mixing one part by volume ofwaterextendable unsaturated polyester resin comprising about 40 percentof a linear unsaturated polyester resin prepared from isophthalic acid,maleic anhydride, diethylene glycol and propylene glycol and about 60percent styrene with two to five parts by volume of water and curingsaid composition in a mold taken from natural keystone.

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